Muscle saving device and method

ABSTRACT

A method, kit, and system to separate muscle fiber prior to threading pedicle screws. By separating the muscle fiber prior to threading the pedicle screws, the muscle fiber does not need to be cut to place rods, which facilitates minimally invasive surgical methods.

FIELD OF THE INVENTION

The present invention relates to a device useful in saving muscle during surgery and, more particularly, to a device useful in minimally invasive spinal surgery to avoid or reduce cutting muscle fiber along the spine.

BACKGROUND OF THE INVENTION

Minimally invasive surgery is preferable to non-minimally invasive surgery. Conventionally, many spinal surgeries include the placement of implants through minimally invasive techniques.

However, conventional methods and devices still require cutting muscle tissue about the spine decreasing the effectiveness of minimally invasive procedure. For example, and much abbreviated from the actual procedure, when placing a rod and two pedicle screws, a surgeon may use a navigation system to locate where the surgeon want to place the screw. The surgeon inserts a guide wire and dilator to the located point and threads the pedicle screw into the pedicle. The surgeon repeats the process for the second pedicle screw. Once the screws are placed, a surgical incision is made to provide access such that a spinal rod can be inserted between the screws. Except by happenstance, the surgeon needs to cut through muscle fiber to insert the spinal rod. Cutting the muscle reduces the effectiveness of the minimally invasive surgery.

It would be advantageous to develop a device and method that would drastically reduce the need to cut muscle fiber during minimally invasive surgical procedures.

SUMMARY OF THE INVENTION

To attain the advantages and in accordance with the purpose of the invention, as embodied and broadly described herein, a method for saving muscle during surgery is provided. The method comprising the steps of locating a first place on a first pedicle to thread a first pedicle screw and inserting a first guide wire at the first place. Placing a first dilator over the first guide wire to separate muscle fiber and expanding and inserting at least one additional dilator over the first dilator to separate the muscle fiber from the first pedicle to a second pedicle. The at least one additional dilator or a subsequent final extending from the first pedicle to the second pedicle exposing a surgical area. The second guide wire can than be placed to thread the second pedicle screw such that the first place and the second place reside in the surgical area in the muscle fiber.

The foregoing and other features, utilities and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments of the present invention, and together with the description, serve to explain the principles thereof. Like items in the drawings are referred to using the same numerical reference.

FIG. 1 is a top elevation view of muscle fiber over a superior pedicle and an inferior pedicle;

FIG. 2 is a side elevation view of FIG. 1;

FIG. 3 is a top elevation view of muscle fiber with a guide wire and dilator placed separating muscle fiber consistent with an embodiment of the present invention;

FIG. 4 is a top elevation view of FIG. 3 with a subsequent dilator separating a portion of muscle fiber extending between superior pedicle and inferior pedicle;

FIG. 5 is a top elevation view of FIG. 3 with a subsequent dilator separating a portion of muscle fiber extending between superior pedicle and inferior pedicle;

FIG. 6 is a top elevation view of FIG. 3 where the muscle fiber is separated exposing the surgical site without needlessly cutting muscle fiber; and

FIG. 7 is a flowchart outlining possible procedural steps useful in using the muscle saving device consistent with the present invention.

DETAILED DESCRIPTION

The present invention will now be described with reference to FIGS. 1 to 7. Referring first to FIGS. 1 and 2, a posterior view and a lateral view of a spinal segment 100 is shown. The Figures are not drawn to scale and only show those potions of the anatomy necessary to understand the present invention. Segment 100 has a layer of muscle 102 comprising substantially parallel muscle fibers 104. Muscle 102 resides posterior to a superior pedicle 106 and an inferior pedicle 108.

To implant a rod between superior pedicle 106 and 108, as mentioned above and with reference to FIG. 3, a surgeon would locate and place a guide wire 302 using conventional navigation technologies on superior pedicle 106, for example, although the surgeon could start with inferior pedicle 108. Next, a dilator 304 is inserted over the guide wire to provide surgical access through the skin. Dilator 304 expands muscle fibers 104 making an exposure area 306 exposing pedicle 106. Conventionally, at this point, a pedicle screw would be threaded over guide wire 302 and dilator 304 would be removed.

Instead of threading a screw and removing dilator 304, the present invention comprises at least one additional dilator, and typically a series of dilators inserted over initial dilator 304. Referring now to FIG. 4, a second dilator 402 is shown inserted over first dilator 304. Second dilator 402 expands exposure area 306 towards the next pedicle, which in this case is inferior pedicle 108. While second dilator 402 is shown having a leading edge 404 giving it a knife, tear drop, or wedge shape, the successive dilators could be any shape including conventional circular shapes. However, it is believed a wedge shape will assist in spreading the muscle fibers. Also, instead of successive dilators, a means of expanding a first dilator is possible. Such, for example, use of a gas to pressurize the dilator and designing the dilator so it can expand in only the desire direction. Alternatively, the dilator may be made out of an expandable material, such as, a shaped memory alloy that can be caused to expand on activation. To be expandable in the desired direction, dilator 402, for example, may comprise at least one substantially rigid portion 402 _(r) and at least one substantially elastic portion 402 _(e). The at least one substantially rigid portion 402 _(r) would reside at least at the portion of dilator 402 that was not to expand. Leading edge 404 may also be relatively rigid if desired to facilitate muscle fiber separation. While the example above is described with a second dilator, first dilator 304 could be expandable making dilator 402 unnecessary and optional.

The dilators according to the present invention could be place over the guide wire and/or screw as described above. Additionally, extenders may or may not be used to assist the surgeon in placement of the dilators as desired.

Referring now to FIG. 5, a segment 100 is shown with a series of dilators 402 installed over first dilator 304. A sufficient number of dilators 402 have been installed such that inferior pedicle 108 is exposed in a second exposure area 502. While all dilators 402 are shown as successively inserted, internal dilators 402 can be removed as desired.

Referring now to FIG. 6, once the appropriate portion of pedicle 108 is exposed, a final dilator 602 is inserted and the dilators 402 are removed providing a surgical access 604 between superior pedicle 106 and inferior 108 along a particular muscle fiber. Guide wires 302 and 606 are located, and pedicles screws can be threaded over guide wires 302 and 606 in a conventional manner. Muscle fiber 104 moves relatively freely in a lateral direction A. Thus, location of guide wires and eventually the pedicle screws can be aligned properly.

Because fibers 104 were spread from superior pedicle 106 to inferior pedicle 108, a rod can be inserted without cutting across muscle fibers 104. The rod would be installed using any conventional method.

For completeness, FIG. 7 is a representative flowchart 700 of using the present invention. First, a surgeon locates a pedicle screw placement on a first pedicle and inserts a guide wire, step 702. Next, the surgeon places a dilator over the guide wire, step 704. A series of dilators are inserted to spread the muscle fiber without cutting the fiber from a first pedicle to a second pedicle, step 706. Successive dilators are external and larger than preceding dilators. Step 706 is repeated until the surgical area between pedicles is exposed. Once the surgical area is exposed, a final dilator is placed extending between first pedicle and second pedicle and exposing a surgical area, step 708. To the extent expandable dilators are used, step 706 would be replaced with a step of expanding the dilator to spread the muscle fiber until the surgical area between pedicles is exposed. Moreover, the final dilator can be the expandable dilator and/or the final dilator that actually spreads muscle. The preceding dilators are removed, step 710. A second pedicle screw placement is located, step 712. Finally, the muscle fibers are laterally aligned such that the surgical area encompasses the first and second pedicle screw placement areas, step 714. Notice, location of the second pedicle screw can be done before or after dilation of the muscle fiber. Moreover, and optionally, preceding internal dilators can be removed subsequent to placement of an external dilator, step 707.

Notice, once the surgical area is exposed, if the final dilator has an access 606 _(a) for the second guide wire, such as a hole or punch sport, the guide wire can be inserted using surgical navigation techniques through the dilator access 606 _(a). The second pedicle screw, with or without extenders, could be threaded, before or after the incision. Notice, because the muscle fiber is spread prior to the incision, less or no muscle fiber needs to be cut. Cutting less muscle fiber increases the effectiveness of minimally invasive procedures.

An embodiment of the present invention and many of its improvements have been described with a degree of particularity. It should be understood that this description has been made by way of example, and that the invention is defined by the scope of the following claims. 

1. A method to save muscle during a spinal surgical procedure, the method comprising: locating a first place on a first pedicle to thread a first pedicle screw; inserting a first guide wire at the first place; inserting a first dilator over the first guide wire to separate muscle fiber and created a dilated area; expanding the dilated area to separate the muscle fiber from the first pedicle to a second pedicle; exposing the surgical area with the muscle fiber separated; and locating a second place of a second pedicle to thread a second pedicle screw, wherein the first place and the second place reside in the surgical area in the muscle fiber.
 2. The method of claim 1, wherein the step of expanding comprises the step of expanding the first dilator at least in a direction toward the second pedicle.
 3. The method of claim 1, wherein the step of expanding comprises inserting at least another dilator over the first dilator to separate muscle fiber.
 4. The method of claim 1, further comprising the step of laterally aligning the muscle fiber with the second place.
 5. The method of claim 1, further comprising the steps of threading a first pedicle screw into the first pedicle, threading a second pedicle screw into the second pedicle, and implanting a rod between the first pedicle and the second pedicle without cutting muscle fiber.
 6. The method of claim 1, wherein the surgical area encompasses at least a third pedicle located between the first pedicle and the second pedicle.
 7. The method of claim 1, further comprising the step of removing all remaining additional dilators after the final dilator is inserted.
 8. The method of claim 1, wherein the step of inserting at least one additional dilator includes inserting a plurality of dilators where each successive dilator is larger than each proceeding dilator.
 9. The method of claim 8, wherein the step of inserting a plurality of dilators includes the step of removing proceeding dilators.
 10. A muscle saving kit useful for minimally invasive surgical procedures, comprising: at least one muscle separating dilator, the at least one muscle separating dilator being sized to separate muscle fibers between a first pedicle and a second pedicle such that a surgical area is exposed; and a final dilator, the final dilator being sized to maintain the separation of the separated muscle fibers and provide surgical access to the surgical area.
 11. The muscle saving kit of claim 10, wherein the at least one muscle separating dilator comprises a plurality of dilators.
 12. The muscle saving kit of claim 10, wherein the at least one muscle separating dilator has a leading edge to facilitate separation of muscle fibers.
 13. The muscle saving kit of claim 12, wherein the muscle separating dilator has a shape selected from the group of shapes consisting of: a knife shape, a tear drop shape, or a wedge shape.
 14. The muscle saving kit of claim 10, wherein the final dilator has a shape selected from the group of shapes consisting of: a substantially circular shape, a substantially elliptical shape, a substantially rectangular shape, or a substantially square shape.
 15. The muscle saving kit of claim 10, wherein the at least one muscle separating dilator is expandable in a direction from the first pedicle to the second pedicle.
 16. A system for installing pedicle screws and at least one connecting device connecting the pedicle screws that saves muscle fiber from being cut, the system comprising: a first guide wire; the first guide wire is located and inserted to determine placement of a first pedicle screw in a first pedicle; a series of successively sized dilators, the series of successively sized dilators comprise at least a first placement dilator to insert over the first guide wire, at least one muscle fiber separating dilator to separate the muscle fiber between the first pedicle and a second pedicle; and a final dilator to maintain the muscle fiber separated during implantation of the first pedicle screw, the second pedicle screw, and the at least one connecting device; and a second guide wire, the second guide wire is located and inserted to determine placement of a second pedicle screw in the second pedicle.
 17. The system of claim 16, further comprising: the first pedicle screw to be threaded over the first guide wire into the first pedicle; and the second pedicle screw to be threaded over the second guide wire into the second pedicle.
 18. The system of claim 16, further wherein the connecting device is a rod.
 19. A muscle saving kit useful for minimally invasive surgical procedures, comprising: at least one expandable dilator, the at least one expandable dilator being sized and shaped to expand and separate muscle fibers between a first pedicle and a second pedicle such that a surgical area is exposed; and at least one access on the at least one expandable dilator, the at least one access positioned to allow a guide wire to be placed after the surgical area is exposed.
 20. The kit of claim 19, wherein the expandable nature of the at least one expandable dilator is accomplished by a plurality of successively sized dilators where each of the successively sized dilators is larger than the proceeding dilator and each dilator is non-expandable. 